prey

n.

mid-13c., "animal hunted for food," also "that which is taken in war," from Old French preie "booty, animal taken in the chase" (mid-12c., Modern French proie), from Latin praeda "booty, plunder, game hunted," earlier praeheda, related to prehendere "to grasp, seize" (see prehensile).

v.

c.1300, "to plunder, pillage, ravage," from prey (n.) and in part from Old French preer, earlier preder (c.1040), from Late Latin praedare, from praeda (see prey (n.)). Its sense of "to kill and devour" is attested from mid-14c. Related: Preyed; preying.

prey on

1.

Plunder or pillage; also, make a profit at someone else's expense, victimize. For example, Vikings preyed on the coastal towns of England, or The rich have been preying on the poor for centuries.
[ Late 1500s
]

2.

Hunt, especially in order to eat, as in Their cat preys on all the rodents in the neighborhood.
[ c. 1600
]

3.

Exert a baneful or injurious effect, as in Guilt preyed on his mind.
[ c. 1700
]